In a wireless communications system, a base station is a radio station that implements information transfer between a mobile terminal and a mobile switching center. An area covered by wireless services that can be provided by a base station is usually referred to as a cell. A mobile terminal in a cell performs information transfer with a mobile switching center by using a base station that serves the cell.
With rapid development of communications technologies, more people begin to carry out instant messaging by using a mobile terminal, so as to meet the need of rapid development of the current society. A base station is used as a macro base station, and a cell covered by wireless services that are provided by the macro base station is used as a macro cell. To increase throughput of the macro cell, multiple small-cell base stations may be deployed in the macro cell covered by the macro base station, and an area covered by wireless services that are provided by each small-cell base station is a small cell.
At present, there are many network deployment manners for deploying small cells in the macro cell to increase the throughput of the macro cell. In one of the network deployment manners, primary pilots and cell identifiers (ID) of the macro cell and the small cells are the same. However, in the foregoing network deployment manner, very strong interference is generated by primary pilot signals, control signals and data signals sent between the macro cell and a small cell and between small cells, so that a mobile terminal cannot receive signals normally. To reduce the interference of signals sent between the macro cell and a small cell or between small cells, different primary pilot spreading codes are set for cells that use a same cell identifier ID, or one or more other auxiliary pilots are added, so that the mobile terminal can receive information normally.
However, when the mobile terminal moves from one small cell to another small cell, because primary pilot spreading codes of the two small cells are different or one or more other auxiliary pilots are added, the mobile terminal needs to be handed over from the previous small cell to the current small cell. At present, there is no handover method that can implement handover of the mobile terminal between the macro cell and a small cell or between small cells that have a same cell ID.